Weight Converter

Enter a non-negative mass, select its current unit, and choose the unit you want to convert to.

Use Swap to reverse the direction. When a valid result exists, the unrounded converted value becomes the new source value.

The input supports ordinary decimals, grouped values such as 10,000, and scientific notation such as 2.5e6.

Each supported unit has a factor representing the number of kilograms in one unit.

The source value is multiplied by its kilogram factor and divided by the target unit's factor.

Using kilograms as a common reference avoids chaining visibly rounded conversions between pounds, ounces, stone, and metric units.

Kilograms, grams, pounds, ounces, stone, and tonnes are units of mass in this converter.

Everyday language often describes a person's or object's mass as weight.

In physics, weight is a force caused by gravity and is commonly measured in newtons.

Mass remains the same when gravitational acceleration changes, while weight force changes.

The kilogram, symbol kg, is the SI base unit of mass.

Since 20 May 2019, it has been defined by fixing the numerical value of the Planck constant rather than by relying on a physical kilogram prototype.

One kilogram contains exactly 1,000 grams, and one gram contains exactly 1,000 milligrams.

Metric prefixes make conversions between these units exact powers of ten.

This converter uses the international avoirdupois pound.

One pound equals exactly 0.45359237 kilogram and contains exactly 16 avoirdupois ounces.

One avoirdupois ounce therefore equals exactly 28.349523125 grams.

The abbreviation lb comes from libra, the Latin name associated with a balance or pound weight.

One stone equals exactly 14 international pounds or 6.35029318 kilograms.

Stone is still commonly encountered in UK and Irish descriptions of body mass.

The converter displays decimal stone because the shared interface converts one numerical unit at a time.

To express a decimal stone result as stone and pounds, keep the whole stone value and multiply the decimal remainder by 14.

The metric tonne, symbol t, equals exactly 1,000 kilograms.

It is different from the US short ton of 2,000 pounds and the Imperial long ton of 2,240 pounds.

Select metric tonnes only when the source measurement means a tonne of 1,000 kilograms.

Short tons and long tons are not included because using one generic ton label would create ambiguity.

An avoirdupois ounce measures mass and is the ounce supported by this calculator.

A fluid ounce measures volume and has different US and Imperial definitions.

A troy ounce is a different mass unit used mainly for precious metals.

Always identify the type of ounce before converting a source value.

Metric-prefix relationships are exact.

The pound-to-kilogram, ounce-to-pound, and stone-to-pound relationships used here are also exact definitions.

Reverse conversions often produce non-terminating decimals and therefore require display rounding.

The table uses the same factors as the live converter.

Non-terminating results are rounded to no more than four decimal places to match the interface.

One pound contains 16 ounces.

To convert the decimal part of a pound result into ounces, multiply the decimal remainder by 16.

For example, 2.5 pounds equals 2 pounds and 8 ounces.

A value such as 2 pounds 5 ounces must first be entered as 2.3125 pounds because 5 divided by 16 equals 0.3125.

One stone contains 14 pounds.

For example, 10.5 stone equals 10 stone and 7 pounds because 0.5 multiplied by 14 equals 7.

A measurement of 11 stone 4 pounds equals approximately 11.2857 stone because 4 divided by 14 is approximately 0.2857.

Avoid rounding the decimal value before performing another conversion.

Grams and kilograms measure mass, while millilitres, litres, cups, and fluid ounces measure volume.

Converting between mass and volume requires the density of the specific substance.

Equal masses of water, flour, oil, sugar, and other materials do not necessarily occupy equal volumes.

Use an ingredient-aware calculator for cooking conversions between grams and cups or millilitres.

The underlying conversion factors remain unrounded during calculation.

Ordinary results display up to four decimal places, while extremely small or large values may use scientific notation.

An exact unit relationship does not make the original measurement exact.

Scale resolution, calibration, source rounding, packaging, moisture, and measurement technique can affect practical accuracy.

The mass conversion runs entirely in the browser.

Entered values and selected units are not uploaded, added to a public URL, or permanently stored.

Clipboard access is requested only when the result copy control is used.